- Adherence to Kansas criteria for Gulf War illness. To aid specificity, these criteria are more involved than CDC criteria Veterans are asked about symptoms in several general categories (e.g., respiratory, gastrointestinal, neuropsychological, sleep disturbances, pain), as well as symptoms (e.g., fatigue, headache) for which no single category is apparent. Gulf War illness criteria symptoms must have persisted or recurred in the year prior to interview and first have been a problem for respondents in 1990 or later. Full criteria are as delineated in Steele 2000.